Within Section 3.1 isotopic ages are determined both by ID-TIMS (isotope dilution thermal ionization mass spectrometry) and SIMS (secondary ion mass spectrometry). These two approaches are complementary, one having excellent accuracy and precision and the other providing unsurpassed spatial resolution. We use ID-TIMS for U-Pb dating of a wide range of silicate, phosphate and oxide minerals (e.g., zircon, titanite, monazite, xenotime, columbite-tantalite) from magmatic and metamorphic rocks and for Rb-Sr and Sm-Nd multimineral isochron dating of metamorphic rocks. SIMS U-Th-Pb dating (mainly applied to the mineral zircon) has a high spatial resolution that allows extracting reliable age information from complex zoned material that cannot be otherwise recovered. In addition, we run an (U,Th,Sm)/He dating facility in collaboration with the University Potsdam (www.geo.uni-potsdam.de/researchgroups.html). We couple isotopic ages with detailed petrologic and tectonic studies, to date the sequence of mineral reactions induced by processes such as rock deformation, metamorphism and ore formation.
Isotopic ages are used to determine the age and/or duration of major geological processes, such as magmatism in subduction zone settings, ultra high-pressure metamorphism, ductile deformation during nappe emplacement, or exhumation-related cooling. We also apply age data to improve our understanding of global-scale processes such as continental break-up and the origin of major mass extinction events. Other key aspects of our isotopic dating work are the development of new SIMS and LA-ICP-MS reference materials and developing analytical protocols for the ID-TIMS dating of ore mineral.